1. Field of the Invention
The present invention relates to telecommunications, and more particularly, to wireless telecommunications.
2. Description of Related Art
In the field of wireless telecommunications, a system typically includes a plurality of base transceiver stations distributed within an area to be serviced by the system. Various users within the area, fixed or mobile, may then access the system, and, thus, other interconnected telecommunications systems, via one or more of the base transceiver stations. Typically, a mobile device maintains communication with the system as the mobile device passes through an area by communicating with one and then another base transceiver station, as the user moves. The mobile device may communicate with the closest base transceiver station, the base transceiver station with the strongest signal, the base transceiver station with a capacity sufficient to accept communications, etc.
Circuit and packet data communication with a wireless subscriber are handled and routed by way of the mobile station identification (“MSID”). The MSID may typically be characterized as either a 10-digit mobile identification number (“MIN”) or a 15-digit International Mobile Subscriber Identifier (“IMSI”). All references to MIN in this document also include the International Roaming MIN [IRM] assigned to service providers outside North America. The MIN is a 10-digit number typically formatted like a dialable 10-digit Mobile Directory Number (MDN). However, MIN is not defined as a dialable number. The IMSI is a 15-digit non-dialable number based on ITU-T Recommendation E.212, and therefore, is not interchangeable with a 10-digit MDN. The format of the IMSI is given below:
IMSI (15 digits)=MCC (3 digits)+MNC (up to 3 digits)+MSIN (all remaining digits)
The mobile country code (MCC) forms the first three digits of the IMSI and identifies the country in which the home system is located. Together with the mobile network code (MNC), which consists of no more than the next 3 digits, the MCC+MNC forms a home system code identifying the home system. The Mobile Subscriber Identification Number (MSIN) uniquely identifies the mobile subscriber within the home system. The IMSI is used in various standards around the world. The IMSI may be programmed into a wireless unit or a Subscriber Identity Module (“SIM”) card by the service provider with whom the wireless unit user has entered into a service agreement.
While MIN and IMSI are not interchangeable, standards have defined a MIN-based IMSI (MBI) to assist in the migration from MIN to IMSI as a subscriber identifier. The MBI is formatted like an IMSI except the first five digits are not assigned to a service provider and, therefore, are not carrier specific for network addressing, routing, billing or settlement purposes. The last 10-digits of the MBI consist of the MIN
Typically, the IMSI as defined by ITU-T Recommendation E.212 is referred to as the true-IMSI or IMSI_T to contrast this IMSI format with the MIN-based-IMSI (also referred to as IMSI_M and MBI).
Unfortunately, due to a lack of clarity in the standards, there is a lack of consistency between service providers, such as CDMA service providers, in their programming and use of MBI and true-IMSI as subscriber identifiers. While each identifier and its use are defined as separate and unique identifiers, they serve similar if not identical functions. However, according to current standards, they are non-interchangeable or interoperable, and this may result in inefficient handling of subscribers roaming across such systems. This problem is being addressed in this invention.